GreigM
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| posted on 18/3/13 at 06:02 PM |
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busa clutch issue
Just got my engine back from a rebuild where amongst other things the clutch basket, one of the plates (the one at the very back) and springs were
changed.
Went for my first test drive today and initially everything felt fine until I got to a straighter bit of road and got to 3rd gear, and with and medium
opening of the throttle the revs were racing up - initially I though I must be spinning the tyres as the road was very cold and greasy, but soon
realised it was the clutch slipping.
So with a bit of experimentation, basically any attempt to accelerate even moderately in 3rd or above would result in slip. Then when I got back down
to crawling speeds I noticed the clutch juddering significantly in 1st and 2nd (specifically pulling away from junctions etc was becoming
difficult).
So got back home, phoned the engine builder who suggested it sounded like "clutch over slow" and it may be something to do with the clutch
slave rod putting to much pressure into the engine. However I took his suggestion to see if I could turn the slave rod by hand, and I could - no
problem (and haven't changed any part of this setup - has always worked well). Tried to re-bleed etc, but same issues.
Any suggestions as to what the issue could be? I'll pull off the clutch cover tonight and pull out the plates, but have never done anything
with the clutch before, so don't really know what to look for.
The engine builder is being very helpful but he's at the other end of the country and so I really need to fix this by myself with his guidance,
so looking for opinions/experiences of what the issue could be.
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Jon Ison
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| posted on 18/3/13 at 06:21 PM |
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You mean clutch over throw ?
If you have over thrown the clutch it will slip but with your foot off the clutch the rod will feel loose as normal.
Only way to be sure is clutch cover off, slacken the clutch spring bolts evenly, you will here the clutch "pop" back into position, if
this is the cause you need a stop on your clutch pedal or if you have one it needs adjusting.
I set mine by putting the car in gear, gradually depress the clutch, as soon as I can push the car that's where I set the pedal stop.
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GreigM
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| posted on 18/3/13 at 06:29 PM |
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There is a stop on the clutch pedal and it was adjusted over a year ago and not had any issues since, but will check its position though like you
suggest. The "pop" test is interesting, will try that as I disassemble later this evening.
The clutch rod only moves about 2mm in total and the bite point isn't very far up the pedal, so have my doubts though.
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Jon Ison
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| posted on 18/3/13 at 06:58 PM |
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But you've had new clutch parts fitted making the assembly "wider" if the stop hasn't been re set then I would bet diamonds
you have over thrown it. The rod only needs to move a few mm to disengage it.
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motorcycle_mayhem
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| posted on 18/3/13 at 07:04 PM |
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Far too many variables and possibles from sticking hydraulics, incorrect adjustment, unhappy plates, an unhappy basket and/or everything else. Check
carefully. My bitter experience, a free moving pushrod when you look at it statically, may not be as free moving when in use. Check that your
Westfield brembo master is allowed to return on it's pivot, and that the Hewland slave cylinder mounted on the engine is returning. Check the
slave's mountings, the earlier brackets failed (mine did), the later ones were stronger, but still broke and distorted. If it's
distorting, it'll bind the pushrod.
Check that the pushrod for tell-tale radial wear marks, where it'll be spinning against it's sleeve. It may even squeak when it does
bind...
The end plates on a clutch are (usually) thicker if OEM, i.e 3.8mm friction, 2.3mm steel (3.0 and 2.0 for the others). If the thicknesses have been
disturbed by replacement of something not the same, things will have changed.
Your steel plates will be purple/darkened if they're unserviceable, pretty obvious. Once these start to slip, it's already scrap.
I've never replaced one, I replace the entire pack, always.
Clutches, like cranks, are consumable items....
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GreigM
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| posted on 18/3/13 at 07:07 PM |
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quote:
Originally posted by Jon Ison
But you've had new clutch parts fitted making the assembly "wider" if the stop hasn't been re set then I would bet diamonds
you have over thrown it. The rod only needs to move a few mm to disengage it.
Makes sense, fingers crossed it isn't anything more serious.
motorcycle_mayhem - I ditched the WF slave a long time ago and have a billet one from SBD. The pushrod looks to be straight and in good condition.
Hoping I don't have to replace all the clutch plates as it doesn't look cheap.
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Jon Ison
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| posted on 18/3/13 at 07:14 PM |
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The fact the pushrod is slack for me rules out all the hydraulic possibilities. Slacken the springs off you will here it pop back, fingers crossed you
haven't damaged the steels.
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SJL
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| posted on 18/3/13 at 09:40 PM |
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Greig on my SBD slave there are washers between the sleeves for the slave mounting bolts. Three at the gearbox end and three between the sleeve and
the slave.
Could you have left some out? That would make the clutch over throw.
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GreigM
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| posted on 18/3/13 at 10:24 PM |
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Don't remember there ever being washers on the slave bolts/sleeves - there certainly aren't any there now and I haven't removed the
slave (although the engine builder may have - will check).
I removed the plates and no "pop" of the clutch going back in. There is some blueing to the steel rings - this would be the worst one,
would it need to be replaced?
Looks like a set of replacement steel parts is around £50 and friction material from £70-£150, so costs aren't as bad as I had feared....if it
makes sense to replace it all I'll do that.
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cosmick
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| posted on 19/3/13 at 09:03 AM |
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Greig,
there is certainly evidence of clutch slip with blue plates. The plates have slipped in the higher gears as the torque has increased. The steel plates
may be warped. Check them out on a surface plate or a flat peice of glass a see if you can slide a feeler gauge underneath whilst holding down the
plate individually. They can be cleaned up with wet and dry if they are flat. Next is the friction plates, they may be worn down thus reducing the
stack height, this in turn will reduce the spring pressure. Finally and most importantly is the springs. These do not last forever and will need
replacing. I would recommend increasing the weight (tension) by at least 10%. Radical sell them or you can try Big CC. I would recommend using
standard friction plates and steels. did your clutch pressure feel softer to the foot than before or can't you remember?
Oh one other thing what oil are you using?
If it can't be fixed with a hammer then its probably an electrical problem.
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GreigM
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| posted on 19/3/13 at 09:10 AM |
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The springs were brand new and uprated items, so shouldn't be an issue.
I'm not averse to putting in a new clutch pack if that will cure the problem - I've seen options from Barnett, EBC or should I stick to
the original suzuki item, and does anyone know the best/quickest way to source them?
Clutch pedal felt fairly light, but it always has done.
Oil is Silkolene Super 4 10w40 semi
[Edited on 19/3/13 by GreigM]
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sdh2903
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| posted on 19/3/13 at 09:53 AM |
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I'm just going through the process of researching parts for my clutch replacement (albeit for an R1) and having trawled the search the general
concensus is that standard steels and frictions with uprated springs is the way to go. Also if you speak to Andy at AB performance he doesn't
reccomend using silkolene oil either. Not sure why but his knowledge is far superior to mine.
I'm not sure on the busa but fowlers were the cheapest uk supplier for oem clutch plates for my R1, for the steels, frictions nad new gasket it
was £195 inc vat. I ended up buying from the states from boats.net including express p and p for $150. Even when i end up paying the duty and vat I
still expect to save around £50.
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cosmick
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| posted on 19/3/13 at 09:58 AM |
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Best to stick with OE clutch parts, even the drag race guys recommend Original parts and tht says something. What make of uprated spring were you
using? Is there a thicker steel plate in the stack? Semi synthetic is fine for oil. Check the bottle for a sign that says JASO MA or JASO MA2. this is
a wet clutch performance test to ensure that the oil does not cause slip by any additives that would increase slipiness.
If it can't be fixed with a hammer then its probably an electrical problem.
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q779
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| posted on 19/3/13 at 10:52 AM |
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Hi Greig
Marshall Loudon in Cambuslang here
I am having exactly the same issue with my Megabusa clutch. I already replaced the slave cylinder as the old one was missing its boot and was full of
crap. I also removed the clutch and inspected it. It had no signs of blueing on the steels or wear on the fibres and the stack height was exactly to
spec (Clutch has only done 770 miles)
Just waiting for delivery of a clutch master cylinder to change that, as I have heard these can sometimes become sticky.
I would be very interested to know what the problem was when you get it sorted and I will let you know how I get on
Cheers
Marshall
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GreigM
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| posted on 19/3/13 at 08:07 PM |
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Will do marshall.....
Talked it over with the engine builder today and we went through checking the thicknesses of the clutch plates and the overall thickness of the pack
and decided something isn't right - so a new clutch pack is on its way.....I'll install this and entirely reset the pedal as above to make
sure there is no reasonable reason for the problem....then test drive.
Will let you all know how it goes!
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Custardpants
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| posted on 19/3/13 at 09:56 PM |
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Be wary of using other than Suzuki plates - I have heard that they have a tendency to break up into larger pieces rather than wear progressively like
the standard ones.
I had exactly the same trouble but discovered that as the clutch plates wore they took up the slack against the clutch pushrod. Filing down the
pushrod is a quick fix but still relieves spring pressure on the plates which is in theory counterproductive. Currently my clutch has the ramp action
disabled for smoother launching but I think this also increases the chances of clutch slip, so I plan to remove it when I do a clutch refresh.
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GreigM
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| posted on 20/3/13 at 11:52 AM |
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Got my new clutch pack (genuine suzuki parts), so going out to fit it soon - just looking up the tightening torques and this chart:
http://www.hayabusa.org/forum/maintenance-do-yourself/93965-gen-1-list-torque-values-most-bolts.html
seems to indicate 7 lb-ft for the clutch cover bolts, but I'm not 100% sure what to use for the 6 bolts which hold the springs in place...should
this be:
Clutch spring set nut @ 7 lb-ft, or...
Clutch spring support nut @ 16.6 lb-ft
Its a '99 engine if that makes a difference.....
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Twin40
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| posted on 20/3/13 at 12:51 PM |
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Be very careful with the 6 retaining bolts, i've recently had to buy a new set as i snapped two of them when tightening up the new clutch
springs. My own stupidity but easily done.
7lb-ft should be plenty, maybe someone else can confirm.....?
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motorcycle_mayhem
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| posted on 20/3/13 at 03:02 PM |
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My experience (worth nothing):
Nothing wrong with Silkolene on my GSXR/TL/R1/Blade lumps, all raced ruthlessly.
Both the GSXR dry sump systems I've used (Nova, Westfield) have made the clutch overheat when abused. Latest set up I have has an oil feel going
down the clutch centre, no problems so far....
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GreigM
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| posted on 20/3/13 at 07:37 PM |
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Fixed!!
New clutch plates in, clutch bled (didn't need to move pedal stop at all, was perfect where it was) and everything working perfectly.....reckon
about 2mm difference between height of old clutch pack and new.
thanks to all for support and suggestions.
Marshall - if you want and help or even a look at how my car is set up sometime just give me a shout.....
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q779
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| posted on 20/3/13 at 07:44 PM |
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Good news Greig
Got confirmation today from Westfield that my new clutch master cylinder 'should' be delivered to me on Saturday (ordered 19th February on
a 1 week delivery!!)
Once I have changed it I'll see how it is. If that doesn't fix it, I may get you to have a look
Cheers
Marshall
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q779
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| posted on 3/4/13 at 10:34 AM |
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Hey Guys
Replaced my Megabusa Clutch Master Cylinder yesterday and have a very frustrating time trying to get the clutch system bled.
The bleed hose has a column of brake fluid with no bubbles, so it would appear that there is no air in the system. However when I pump the pedal ,
I can't get any pressure in the system and the rod from the slave cylinder doesn't move at all.
Any ideas?
Cheers
Marshall
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q779
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| posted on 3/4/13 at 03:44 PM |
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Now sorted - pumping fluid through the bleed nipple back through the slave cylinder, hose, master cylinder and out the reservoir cleared the air. A
quick bleed and clutch was working fine.
Even better, the change of master cylinder has cured my clutch slip
Cheers
Marshall
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Custardpants
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| posted on 3/4/13 at 06:47 PM |
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What master cylinder did you change to out of interest? Currently trying to replace / substitute both my master and slave cylinders for something
better.
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GreigM
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| posted on 5/4/13 at 09:43 PM |
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thats good news marshall......my clutch performed flawlessly on a couple of track days this week so very pleased its sorted...now onto my next (small)
issue which is a cold idle issue.....
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